Assign the values of one array to be the keys in a new array

Question

Assign the values of one array to be the keys in a new array

Here is an example of an array:

[
  {date:'27-06-2021',name:'John Doe',count:2},
  {date:'29-06-2021',name:'John Doe',count:1},
  {date:'29-06-2021',name:'George Newman',count:1},
]

I am looking to reformat this array into a new structure where the names become keys and the counts add up based on the dates.

The desired outcome should look like this:

[
  {date:'27-06-2021',John Doe:2,sumCount:2},
  {date:'29-06-2021',John Doe:1,George Newman:1,sumCount:2},
]

Is there a way to achieve this transformation? Any suggestions would be appreciated. Thank you!

javascript arrays

Answer 1

Answer №1

One way to improve the array organization is by implementing some basic logic.

const input = [
  { date: '27-06-2021', name: 'John Doe', count: 2 },
  { date: '29-06-2021', name: 'John Doe', count: 1 },
  { date: '29-06-2021', name: 'George Newman', count: 1 },
]

const output = [];
input.forEach((record) => {
  searchNode = output.find((node) => node.date === record.date);
  if(searchNode) {
    searchNode.sumCount += 1;
    if (searchNode[record.name]) {
      searchNode[record.name] += 1
    } else {
      searchNode[record.name] = 1
    }
  }
  else {
    pushNode = {
      date: record.date,
      sumCount: record.count,
    };
    pushNode[record.name] = 1;
    output.push(pushNode);
  }
})
console.log(output);

Answer 2

One way to improve the array organization is by implementing some basic logic.

const input = [
  { date: '27-06-2021', name: 'John Doe', count: 2 },
  { date: '29-06-2021', name: 'John Doe', count: 1 },
  { date: '29-06-2021', name: 'George Newman', count: 1 },
]

const output = [];
input.forEach((record) => {
  searchNode = output.find((node) => node.date === record.date);
  if(searchNode) {
    searchNode.sumCount += 1;
    if (searchNode[record.name]) {
      searchNode[record.name] += 1
    } else {
      searchNode[record.name] = 1
    }
  }
  else {
    pushNode = {
      date: record.date,
      sumCount: record.count,
    };
    pushNode[record.name] = 1;
    output.push(pushNode);
  }
})
console.log(output);

Answer 3

Answer №2

To achieve this task, you can utilize the Array.prototype.reduce method to gather the dates into a dictionary where the dates serve as unique keys. Then, you can employ Object.values() to extract the values from the dictionary.

const transformedData = Object.values(data.reduce((acc, cur) => {
    // For clarity purposes, I have moved these variables here
    const { date, name, count } = cur;

    // Build the dictionary using `date` as the key
    if (date in acc) {
        acc[date].sumCount += count;
    } else {
        acc[date] = {
            date,
            sumCount: count
        };
    }

    // Names are used as keys to keep track of individual counts
    // If name is nullish, it starts at 0
    acc[date][name] = (acc[date][name] ?? 0) + count;

    return acc;
}, {}));

Here's a proof-of-concept example:

const data = [{
    date: '27-06-2021',
    name: 'John Doe',
    count: 2
  },
  {
    date: '29-06-2021',
    name: 'John Doe',
    count: 1
  },
  {
    date: '29-06-2021',
    name: 'George Newman',
    count: 1
  },
];

const transformedData = Object.values(data.reduce((acc, { date, name, count }) => {
  if (date in acc) {
    acc[date].sumCount += count;
  } else {
    acc[date] = {
      date,
      sumCount: count
    };
  }
  
  acc[date][name] = (acc[date][name] ?? 0) + count;
  
  return acc;
}, {}));

console.log(transformedData);

Answer 4

To achieve this task, you can utilize the Array.prototype.reduce method to gather the dates into a dictionary where the dates serve as unique keys. Then, you can employ Object.values() to extract the values from the dictionary.

const transformedData = Object.values(data.reduce((acc, cur) => {
    // For clarity purposes, I have moved these variables here
    const { date, name, count } = cur;

    // Build the dictionary using `date` as the key
    if (date in acc) {
        acc[date].sumCount += count;
    } else {
        acc[date] = {
            date,
            sumCount: count
        };
    }

    // Names are used as keys to keep track of individual counts
    // If name is nullish, it starts at 0
    acc[date][name] = (acc[date][name] ?? 0) + count;

    return acc;
}, {}));

Here's a proof-of-concept example:

const data = [{
    date: '27-06-2021',
    name: 'John Doe',
    count: 2
  },
  {
    date: '29-06-2021',
    name: 'John Doe',
    count: 1
  },
  {
    date: '29-06-2021',
    name: 'George Newman',
    count: 1
  },
];

const transformedData = Object.values(data.reduce((acc, { date, name, count }) => {
  if (date in acc) {
    acc[date].sumCount += count;
  } else {
    acc[date] = {
      date,
      sumCount: count
    };
  }
  
  acc[date][name] = (acc[date][name] ?? 0) + count;
  
  return acc;
}, {}));

console.log(transformedData);

Answer 5

Answer №3

let information = [
  {date:'27-06-2021',name:'John Doe',amount:2},
  {date:'29-06-2021',name:'John Doe',amount:1},
  {date:'29-06-2021',name:'George Newman',amount:1},
];

information = information.map(function(person)
{
  person[person['name']] = person['amount'];
  delete person['name'];
  delete person['amount'];
  
  return person;
});

console.log(information);

Answer 6

let information = [
  {date:'27-06-2021',name:'John Doe',amount:2},
  {date:'29-06-2021',name:'John Doe',amount:1},
  {date:'29-06-2021',name:'George Newman',amount:1},
];

information = information.map(function(person)
{
  person[person['name']] = person['amount'];
  delete person['name'];
  delete person['amount'];
  
  return person;
});

console.log(information);

Assign the values of one array to be the keys in a new array

Answer №1

Answer №2

Answer №3

Similar questions

Is it possible to encounter an invalid index error when removing a key from an array?

Problems arising from Jquery append functionality

how to use jQuery to sort appended data

Utilize a function to send an AJAX email

Arrangement of elements in MongoDB

Split a string into numbers and store them in an array in Matlab

Incorporating image links within React components

Use Javascript to display an image based on the date, otherwise hide the div

Semantic UI dropdown field not displaying selected option text

Incorporating the fadeout technique in conjunction with the append() function

What is the JavaScript event object all about?

Shopping Dialog with Bootstrap (nakupanda) captures form input [JSFiddle]

Material UI allows for the creation of numbered lists with ease. This

Stopping the continuous re-sending of a script via Ajax when a key is pressed

Retrieve the element by clicking on its individual tooltip

Objects within an array are not sorted based on their properties

When using jQuery, the search for the ID within an iframe may fail if the specified condition

Error: The ng-click directive is encountering a parsing syntax error. The token 'Object' is unexpected and is causing the error, it is expected to be enclosed in

Is there a pythonic technique for comparing values within an array?

Show Data on the Right-hand Side